A Megabus coach is escorted away from the scene on the M6 toll motorway near Weeford, UK, after it was shut following a “police-led incident”.

London, July 5: The British security services will be very relieved when the London 2012 Olympics, due to start on July 27, are over and the Games pass without incident.

But they are apprehensive that with the eyes of the world on the UK, the Olympics will offer a tempting target to Al Quaeda and other terrorist groups.

Either the security services are very jumpy or they are taking no chances. What happened today is a case in point.

An early morning coach carrying 48 passengers from Preston to London was intercepted by armed police, backed up by the army, on the M6 motorway at a toll station at Weeford, near Lichfield.

What triggered this overwhelming show of fire power was that someone on the bus had spotted a passenger “pouring liquid into a smoking bag” and tipped off the police.

“At around 8.20am today we received a report from a genuinely concerned member of the public about suspicious activity on a coach,” said a spokeswoman for Staffordshire police. “Given the nature of the report we responded swiftly and proportionately, treating the information as credible and extremely seriously.”

The busy motorway was shut in both directions, while police searched the passengers one by one. Military personnel, police dog handlers, firefighters and other specialist units were also at the scene.

In the end, the bus with all its passengers was escorted away in a police cavalcade.

“We are also not treating anyone as a suspect,” the spokeswoman said later.

This means the entire tamasha might have been caused by someone unscrewing a flask containing steaming masala chai at the bottom of his bag. But equally it could have something deadly. Given the kind of tricks terrorists attempt to slip liquid explosives onto aircraft, any Asian looking man, especially if bearded or wearing Islamic clothing, does not get the benefit of the doubt if he is seen doing something “suspicious”.

But neither do the security forces act without reason. Today, six people were arrested in the London area on “on suspicion of the commission, preparation or instigation of acts of terrorism”. What will cause extreme concern is that some of them are British nationals – which means the terror threat could come from “sleepers” born and brought up in Britain.

The six, who are being held at a south-east London police station, include a 24-year-old man who had a Taser gun fired at him when he was arrested in east London – not far from the Olympics venue.

This must have been deeply worrying for the police. If the threat is not an external one but comes from people embedded in the local community, police cannot go on fishing expeditions but will have to rely on good intelligence before being able to act.

A 29-year-old man was arrested in the street in west London, a 21-year-old man and a 30-year-old woman were held at separate residential premises in west London, and two other men, aged 18 and 26, were arrested with the 24-year-old in east London.

In the Commons yesterday, MPs voted last night to add the Indian Mujahideen to the list of 47 other proscribed organisations.

The group has been linked with a number of terrorist attacks in India, some against tourists, as part of its efforts to turn the country into an Islamic state, governed under Sharia law, Home Office minister James Brokenshire told the Commons.

Brokenshire said: “The organisation has frequently perpetrated attacks against civilian targets, such as markets, with the intention of maximising casualties. For example, in May 2008, a spate of bomb detonations in the city of Jaipur killed 63 and in September of last year, while an explosion outside the high court in Delhi reportedly killed 12 and injured 65. IM has sought to incite sectarian hatred in India by deliberately targeting Hindu places of worship such as an attack in the city of Varanasi, which killed a child in December 2010.”

Labour MP Keith Vaz, chairman of the Commons select committee on Home Affairs, said: “The international community should join together in criminalising this organisation, which has killed innocent civilians and uses violence indiscriminately.”